JP2013010007A - Superhydrophilic material, medical material and medical appliance - Google Patents

Abstract

A method for modifying a DLC film capable of improving the hydrophilicity of the DLC film and efficiently imparting functions such as biocompatibility can be realized.
A superhydrophilic material includes a base material and a DLC film formed on the surface of the base material and having a hydrophilic functional group. The contact angle of water on the surface of the DLC film is 10 degrees or less, and an intermediate layer for improving the adhesion between the base material and the DLC film is provided between the base material and the DLC film. The thickness of the DLC film is 0.01 μm or more and 3 μm or less, and the thickness of the intermediate layer is 0.01 μm or more and 0.3 μm or less.
[Selection] Figure 3

Description

  The present invention relates to a super-hydrophilic material, a medical material, and a medical instrument, and particularly relates to a material excellent in biocompatibility.

  A diamond-like thin film (DLC film) has a hard, dense, and inert surface, so it should be formed on the surface of a substrate made of an inorganic material such as metal or ceramics and an organic material such as resin. Thus, properties such as wear resistance, corrosion resistance and surface smoothness can be imparted to the surface of the substrate.

  For example, it is known that the surface of a mold or a jig / tool is coated with a DLC film to improve durability or improve releasability. Moreover, since it is a very smooth and inert surface, it is also expected as a method of surface-treating a base material of a medical device that dislikes interaction with a biological substance (for example, Patent Document 1 and Non-Patent Document 1). See).

  Furthermore, the present inventors have reported a method for introducing a reactive site into the DLC film by irradiating the DLC film with plasma (see, for example, Patent Document 2). By reactive plasma, a reactive site such as a radical is introduced into the DLC film, and the biocompatible polymer can be graft polymerized using the introduced radical as a starting point. Moreover, after introducing radicals, functional groups such as hydroxyl groups can be generated by exposure to the atmosphere, and various modifications can be made to the DLC film by using the generated functional groups. Thus, by modifying the DLC film, various functions such as biocompatibility can be added, and a material having both durability and functionality can be realized.

JP-A-10-248923 International Publication No. 2005/97673 Pamphlet

Haruo Ito et al., “Biomaterials”, 1985, Volume 3, p. 45-53

  However, as a result of the study by the present inventors, it has been clarified that the conventional method for modifying a DLC film has the following problems. In the conventional method for modifying a DLC film, radicals are generated by cleaving the carbon-carbon bond of the DLC film by irradiating the DLC film covering the surface of the substrate with plasma. The radicals formed by cleaving the carbon-carbon bond of the DLC film are unstable and easily disappear, and the polymer must be grafted immediately after the DLC film is irradiated with plasma.

  In addition, since radicals are unstable, the number of radicals contributing to polymer grafting cannot be made constant even if the time from the irradiation of plasma to the start of polymerization is made constant. As a result, the coating state of the polymer varies between lots, and functions such as biocompatibility cannot be imparted with good reproducibility.

  Furthermore, even when a hydrophilic functional group such as a hydroxyl group is introduced by exposing the DLC film into which the radical has been introduced to the atmosphere, the reaction between the radical and oxygen does not proceed sufficiently. For this reason, the hydrophilicity of the DLC film is not sufficiently improved. Moreover, even if the hydrophilicity is improved once, the hydrophilicity deteriorates again with the passage of time.

  The present invention solves the above-described conventional problems, and improves the hydrophilicity of the DLC film and realizes a DLC film modification method capable of efficiently imparting functions such as biocompatibility. With the goal.

  In order to achieve the above object, the present invention provides a method for modifying a DLC film, a first plasma irradiation step for forming a reactive site in the DLC film, and a second method for converting a reactive site into a hydrophilic functional group. And a plasma irradiation step.

  The method for modifying a diamond-like thin film according to the present invention comprises a step (a) of forming a diamond-like thin film on the surface of a substrate, and irradiating the diamond-like thin film with a first plasma to thereby change the reactive site. A step (b) of generating a hydrophilic functional group by reacting a reactive site with oxygen by irradiating the diamond-like thin film with a second plasma containing at least oxygen. ).

  The method for modifying a diamond-like thin film of the present invention includes a step of introducing a hydrophilic functional group by reacting a reactive site with oxygen by irradiating the diamond-like thin film with a second plasma containing at least oxygen. Therefore, the reactive site formed on the surface of the diamond-like thin film by the first plasma irradiation can be surely made into a hydrophilic functional group. For this reason, not only durability but the hydrophilic function can be efficiently provided to a base material. Therefore, durability and hydrophilicity can be imparted to materials in various fields including medical materials. Further, the surface of the diamond-like thin film can be further modified by using the introduced functional group.

  In the method for modifying a diamond-like thin film of the present invention, in step (c), the contact angle of water in the diamond-like thin film is preferably 10 degrees or less. With such a configuration, a so-called superhydrophilic material can be realized.

  In the method for modifying a diamond-like thin film of the present invention, the first plasma is an organic material containing argon, xenon, neon, helium, krypton, nitrogen, oxygen, ammonia, hydrogen, water vapor, chain or cyclic hydrocarbon, and oxygen. It is preferably a plasma of one gas selected from the group consisting of a compound and an organic compound containing nitrogen, or a mixed gas consisting of two or more.

  In the method for modifying a diamond-like thin film of the present invention, the second plasma is a plasma of one gas selected from the group consisting of oxygen, air, water vapor, and an organic compound containing oxygen, or a mixed gas consisting of two or more. It is preferable.

  In the method for modifying a diamond-like thin film of the present invention, the hydrophilic functional group preferably contains a carboxyl group.

  The method for modifying a diamond-like thin film of the present invention may further include a step (d) of fixing a functional material on the surface of the diamond-like thin film using a hydrophilic functional group after the step (c). Preferably, in the step (d), a hydrophilic functional group and a functional group contained in the functional material may be covalently bonded. Further, the step (d) may include a step of activating the hydrophilic functional group and a step of performing graft polymerization using the activated hydrophilic functional group as a starting point.

  In the method for modifying a diamond-like thin film of the present invention, the functional material is preferably a biocompatible polymer.

  In this case, the biocompatible polymer is a polyurethane, polyacrylamide, polyethylene oxide, polyethylene carbonate, polyethylene, polyethylene glycol, polyvinyl pyrrolidone, polypropylene carbonate, polyamide, fibrin, phospholipid polymer, hydrophobic hydrophilic microphase separation polymer, Hydroxyethyl methacrylate polymer or copolymer, vinyl pyrrolidone polymer or copolymer, fluorine-containing monomer polymer or copolymer, Si-containing monomer polymer or copolymer, and vinyl ether polymer or copolymer It is preferably at least one polymer selected from the group consisting of a coalescence or an esterified product of the polymer.

  In the method for modifying a diamond-like thin film of the present invention, the functional material may be a biodegradable polymer that carries an antithrombotic drug and releases the supported drug.

  In this case, the biodegradable polymer is polylactic acid, polyglycolic acid, a copolymer of polylactic acid and polyglycolic acid, collagen, gelatin, chitin, chitosan, hyaluronic acid, polyamino acid, starch, poly-ε-caprolactone Preferably, the polymer is at least one polymer selected from the group consisting of polyethylene succinate, and poly-β-hydroxyalkanoate. The biodegradable polymer may contain a plasticizer.

  The method for modifying a diamond-like thin film of the present invention further includes an intermediate layer forming step of forming an intermediate layer for improving the adhesion between the base material and the diamond-like thin film on the surface of the base material before step (a). It is preferable.

  In this case, the intermediate layer is preferably an amorphous film mainly composed of silicon and carbon.

  The method for producing a medical material according to the present invention is characterized by using the method for modifying a diamond-like thin film according to the present invention.

  The medical device manufacturing method according to the present invention is characterized by using the medical material manufacturing method of the present invention.

  In the method for manufacturing a medical device of the present invention, the medical device may be in direct contact with human tissue.

  In the method for producing a medical device of the present invention, the medical device is a stent, a catheter, a balloon catheter, a guide wire, a pacemaker lead, an indwelling device, an injection needle, a scalpel, a vacuum blood collection tube, an infusion bag, a prefilled syringe, a wound. Any one of the holding parts is preferable.

  The superhydrophilic material according to the present invention comprises a base material and a diamond-like thin film having a hydrophilic functional group formed on the surface of the base material, and the contact angle of water on the surface of the diamond-like thin film is 10 degrees or less. It is characterized by being.

  The superhydrophilic material of the present invention has a contact angle of water of 10 degrees or less on the surface of the diamond-like thin film, and has excellent durability as well as superhydrophilicity. Therefore, it can be used as a material in various fields including medical materials that require durability and hydrophilicity.

  In the superhydrophilic material of the present invention, the hydrophilic functional group preferably contains at least a carboxyl group.

  In the superhydrophilic material of the present invention, the substrate is preferably a metal material, a ceramic material, a polymer material, or a composite thereof.

  In the superhydrophilic material of the present invention, it is preferable that an intermediate layer for improving the adhesion between the base material and the diamond-like thin film is provided between the base material and the diamond-like thin film.

  In the superhydrophilic material of the present invention, the intermediate layer is preferably an amorphous film mainly composed of silicon and carbon.

  The medical material according to the present invention is characterized by using the superhydrophilic material of the present invention.

  The medical instrument according to the present invention is characterized by using the medical material of the present invention.

  In the medical instrument of the present invention, the medical instrument may be in direct contact with human tissue.

  In the medical instrument of the present invention, the medical instrument includes a stent, a catheter, a balloon catheter, a guide wire, a pacemaker lead, an indwelling device, an injection needle, a scalpel, a vacuum blood collection tube, an infusion bag, a prefilled syringe, and a wound holding part. Any one is preferred.

  According to the DLC film modification method and super-hydrophilic material, medical material, medical device and manufacturing method thereof according to the present invention, the hydrophilicity of the DLC film is improved and functions such as biocompatibility are efficiently imparted. It is possible to perform well, and it is possible to realize a method for modifying a DLC film and a superhydrophilic material, a medical material, a medical instrument, and a manufacturing method thereof.

It is the schematic which shows the ionization vapor deposition apparatus used in one Example of this invention. It is the schematic which shows the plasma irradiation apparatus used in one Example of this invention. (A)-(c) is a chart which shows the result of the X-ray photoelectron spectroscopy analysis of the DLC film based on one Example of this invention, (a) performed 1st plasma irradiation and 2nd plasma irradiation. It is a DLC film, (b) is a DLC film not subjected to plasma irradiation, and (c) is a DLC film subjected to only the first plasma irradiation. It is a graph which shows the time-dependent change of the wettability of the DLC film which concerns on one Example of this invention. It is a chart which shows the result of the X-ray photoelectron spectroscopy which evaluated introduction | transduction of the polymer to the DLC film which concerns on one Example of this invention.

  An embodiment of the present invention will be described with reference to the drawings. In the method for modifying a DLC film of this embodiment, first, a diamond-like thin film (DLC film) that covers the surface of the substrate is formed.

  Organic and inorganic materials including metal materials and resin materials can be used for the substrate.

  Specifically, although not particularly limited, for example, a metal such as iron, nickel, chromium, copper, titanium, platinum, tungsten, or tantalum can be used as the base material. Further, these alloys are stainless steel such as SUS316L, shape memory alloy such as Ti—Ni alloy or Cu—Al—Mn alloy, Cu—Zn alloy, Ni—Al alloy, titanium alloy, tantalum alloy, platinum alloy or An alloy such as a tungsten alloy can also be used. Moreover, bioactive ceramics, such as oxides, such as aluminum, a silicon | silicone, or a zircon, nitride, or carbide | carbonized_material, or ceramics which have bioactivity, such as apatite or a biological glass, may be sufficient. Further, it may be a polymer resin such as polymethyl methacrylate (PMMA), high-density polyethylene or polyacetal, a silicon polymer such as polydimethylsiloxane, or a fluorine polymer such as polytetrafluoroethylene.

  These materials may be materials such as wires, tubes and flat plates. Furthermore, it may be formed in a specific shape such as a medical instrument or in the middle of formation. Medical devices include, for example, stents, catheters, balloon catheters, guide wires, pacemaker leads, indwelling devices, injection needles, scalpels, vacuum blood collection tubes, infusion bags, prefilled syringes, wound holding parts, artificial heart valve membranes and artificial joints Etc. are included.

  What is necessary is just to form the DLC film which covers the surface of a base material using a known method. For example, sputtering, DC magnetron sputtering, RF magnetron sputtering, chemical vapor deposition (CVD), plasma CVD, plasma ion implantation, superimposed RF plasma ion implantation, ion plating, arc ion play It can be formed on the surface of the substrate by a coating method, an ion beam deposition method, a laser ablation method or the like. The thickness is not particularly limited, but is preferably in the range of 0.005 to 3 μm, more preferably in the range of 0.01 to 1 μm.

  The DLC film can be directly formed on the surface of the base material, but an intermediate layer may be provided between the base material and the DLC film in order to more firmly adhere the base material and the DLC film. As the material for the intermediate layer, various materials can be used depending on the type of substrate, but silicon (Si) and carbon (C), titanium (Ti) and carbon (C), or chromium (Cr) and carbon. A known film such as an amorphous film made of (C) can be used. Although the thickness is not specifically limited, the range of 0.005-0.3 micrometer is preferable, More preferably, it is the range of 0.01-0.1 micrometer.

  The intermediate layer can be formed using a known method. For example, a sputtering method, a CVD method, a plasma CVD method, a thermal spraying method, an ion plating method, an arc ion plating method, or the like may be used.

By performing the first plasma irradiation on the DLC film formed so as to cover the base material, a reactive site such as a radical is generated in the DLC film. The plasma for generating the reactive site may be any plasma that can generate an oxidation start point by cutting a carbon-carbon bond existing on the surface of the DLC film. Specifically, for example, argon (Ar), neon (Ne), helium (He), krypton (Cr), xenon (Xe), nitrogen gas (N ₂ ), oxygen gas (O ₂ ), ammonia gas (NH ₄ ), A gas such as hydrogen gas (H ₂ ) or water vapor (H ₂ O), or a plasma using a mixed gas thereof as a plasma gas species may be used.

  In the manufacturing method of the medical material of this embodiment, after performing 1st plasma irradiation, 2nd plasma irradiation is performed. By the second plasma irradiation, a reactive site such as a radical formed by the first plasma irradiation is reacted with oxygen to generate a hydrophilic functional group containing oxygen such as a carboxyl group.

  The reactive site generated by the first plasma irradiation is expected to be converted into a carboxyl group, a hydroxyl group, and the like by exposure to an atmosphere containing oxygen or water. However, the amount of carboxyl groups and hydroxyl groups generated when the DLC film after the first plasma irradiation is simply exposed to an atmosphere containing oxygen or water is very small, and a sufficiently hydrophilic functional group is not present. Cannot be generated. However, by performing the second plasma irradiation, it can be efficiently converted into a hydrophilic functional group such as a carboxyl group.

  The second plasma irradiation may be performed by irradiation with plasma containing oxygen atoms. Specifically, plasma irradiation is performed using oxygen, air, water vapor, a gas such as an organic compound containing oxygen atoms, or a mixed gas thereof as a plasma gas species. Can be done.

  The DLC film subjected to the second plasma irradiation is hydrophilic due to a carboxyl group or the like introduced on the surface. For this reason, it still has excellent biocompatibility and can be used as a medical instrument such as a stent.

  Moreover, you may fix functional materials, such as a polymer which has biocompatibility, on the surface of a DLC film using the carboxyl group introduce | transduced on the surface of the DLC film.

  The functional material may be fixed by a known method. For example, a functional group in a functional material and a hydroxyl group or a carboxyl group are fixed via a coupling reagent, or a functional group that reacts with a hydroxyl group or a carboxyl group is introduced into the functional material, What is necessary is just to make it react and fix with the functional group of the DLC film surface.

  In addition, the hydroxyl group and the carboxyl group are substituted with a functional alkoxysilane derivative such as 3-aminopropyltrimethoxysilane, a functional carboxylic acid derivative such as 2-mercaptoacetic acid, a diisocyanate derivative, 2-methacryloyloxyethyl isocyanate, and 2-acryloyloxyethyl. By reacting with isocyanate, N-methacryloyl succinimide, N-acryloyl succinimide or the like, it can be easily converted into an amino group, an isocyanate group, a vinyl group or the like. The functional material may be fixed using such a converted functional group.

  In addition, the functional material may be fixed by ionic bonding with a carboxyl group or the like instead of being fixed by a covalent bond. In this case, a carboxyl group or the like may be converted to another ionic functional group. By ionic bonding, even if the functional material is an inorganic material such as hydroxyapatite, it can be easily introduced onto the surface of the DLC film.

  The functional material fixed on the surface of the DLC film may be any material, but when used as a medical material, a biocompatible polymer may be used. For example, parylene, polyethylene, polyethylene terephthalate, ethylene vinyl acetate, silicon, polyethylene oxide (PEO), polybutylmethyl acrylate, polyacrylamide, polyvinyl pyrrolidone, polyethylene carbonate or polypropylene carbonate, polyurethane, or segmented polyurethane or polyether It is possible to use a synthetic polymer such as a blend of block polyurethane and dimethyl silicon or a block copolymer. Natural polymers such as peptides, proteins, nucleobases, sugar chains, chitin or chitosan may also be used.

  Further, the DLC film may be provided with functionality such as antithrombogenicity instead of biocompatibility. In this case, it is preferable to fix a polymer containing the drug therein and having the ability to release the drug at a constant rate.

  For example, a biodegradable polymer carrying an antithrombotic drug may be fixed. Even if the biodegradable polymer is decomposed and the DLC film is exposed, there is no problem because the underlying DLC film is hydrophilic. Biodegradable polymers include, for example, polyglycolic acid, copolymers of lactic acid and glycolic acid, poly DL lactic acid (DL-PLA), poly L lactic acid (L-PLA), lactide, polycaprolactone (PCL), collagen, gelatin , Chitin, chitosan, hyaluronic acid, poly-L-glutamic acid, poly-L-lysine and other polyamino acids, starch, poly-ε-caprolactone, polyethylene succinate, poly-β-hydroxyalkanoate, and the like. In addition, any biodegradable polymer can be used as long as it is enzymatically or non-enzymatically degraded in vivo, the degradation product does not exhibit toxicity, and can release the drug. .

  Antithrombotic drugs carried on biodegradable polymers are antiplatelet agents, anticoagulants, antifibrin and antithrombin, such as heparin sodium, low molecular weight heparin, hirudin, argatroban, forskolin, salvocrelate hydrochloride, Bapiprost, prostacyclin, prostacyclin congener, dextran, D-fe-pro-arg-chloromethyl ketone (synthetic antithrombin), dipyridamole, glycoprotein IIb / IIIa platelet membrane receptor antibody, vitronectin receptor antagonist and thrombin inhibitor Etc. may be used.

  In addition, a plasticizer may be added to the polymer in order to accelerate the degradation of the polymer by the living body and efficiently release the drug. As the plasticizer, for example, an ester plasticizer of tartaric acid, malic acid or citric acid, or another plasticizer whose safety against living bodies has been confirmed may be used.

  It is also possible to fix a polymer having a function other than biocompatibility and biodegradability depending on the application.

  Further, the polymer may be fixed by activating a functional group such as a carboxyl group by irradiation with plasma, ultraviolet rays, radiation or the like, and graft-polymerizing the monomer using the activated functional group as a starting point. The energy required for the activation of the carboxyl group is much smaller than the carbon-carbon bond cleavage. Therefore, the activation of the carboxyl group is easier than when radicals are introduced into the surface of the DLC film. For this reason, it is possible to perform graft polymerization onto the DLC film efficiently.

(Example)
Hereinafter, the DLC film modification method according to the present invention will be described more specifically with reference to examples.

  In this example, a high-speed tool steel (JIS standard SKH51) having a size of 12 mm square and a thickness of 5 mm was used as the base material.

FIG. 1 schematically shows an ionization vapor deposition apparatus used in this example. Argon and benzene (C ₆₎ as ion sources are connected to a DC arc discharge plasma generator 2 provided in a vacuum chamber. This is an ordinary ionization deposition apparatus for solidifying a DLC film on the target 1 by colliding the plasma generated by introducing the H ₆ ) gas with the target 1 biased to a negative voltage.

Was set in the chamber of the ionization vapor deposition apparatus shown in FIG. 1 the substrate, so that argon gas (Ar) pressure becomes ^{10 -1 Pa~10 -3 Pa (10 -3} Torr~10 -5 Torr) in the chamber Then, Ar ion was generated by discharging, and bombard cleaning was performed for about 30 minutes to cause the generated Ar ions to collide with the surface of the substrate.

Subsequently, tetramethylsilane (Si (CH ₃ ) ₄ ) is introduced into the chamber for 3 minutes, and an amorphous intermediate layer having a thickness of 20 nm is mainly formed of silicon (Si) and carbon (C).

After forming the intermediate layer, C ₆ H ₆ gas is introduced into the chamber, and the gas pressure is set to 10 ⁻¹ Pa. The C ₆ H ₆ ionized by performing continuously introduced while discharging the C ₆ H ₆ at 30 mL / min, subjected to ionizing deposition about 2 minutes, the DLC film having a thickness of 30nm on a surface of a substrate Formed.

  When forming the DLC film, the target voltage is 1.5 kV, the target current is 50 mA, the filament voltage is 14 V, the filament current is 30 A, the anode voltage is 50 V, the anode current is 0.6 A, the reflector voltage is 50 V, and the reflector current is 6 mA. It was. Moreover, the temperature of the base material at the time of formation was about 160 ° C.

  The intermediate layer is provided in order to improve the adhesion between the base material and the DLC film, and may be omitted when sufficient adhesion between the base material and the DLC film can be secured.

In this embodiment, a C ₆ H ₆ single gas is used as the carbon source, but other hydrocarbon raw materials may be used. Alternatively, a DLC film containing fluorine may be formed on the surface of the base material using a mixed gas of a hydrocarbon raw material such as C ₆ H ₆ and a chlorofluorocarbon gas such as CF ₄ .

  Next, radicals were introduced to the surface of the DLC film by irradiating the DLC film formed on the surface of the substrate with plasma. FIG. 2 schematically shows the plasma irradiation apparatus used in this example.

  As shown in FIG. 2, the plasma irradiation apparatus used in the present embodiment is a general plasma irradiation apparatus, and an electrode 23 and an electrode are respectively provided on the bottom surface and the body portion of a chamber 21 to which a vacuum pump 22 is connected and gas replacement is possible. 24 is provided. A high frequency is applied to the electrode 23 and the electrode 24 from a high frequency power supply 25 through a matching network 26 to generate plasma inside the chamber, and the target 11 placed on the electrode 23 is irradiated with the plasma.

First, the 1st plasma irradiation which generates a radical was performed with respect to the base material in which the DLC film was formed. After the base material on which the DLC film was formed was set inside the chamber of the plasma irradiation apparatus, acetylene (C ₂ H ₂ ) was flowed to adjust the internal pressure of the chamber to 133 Pa. Subsequently, a high frequency power source (manufactured by Adtech Plasma Technology, AX-300 type; frequency 13.56 MHz) was applied to the electrode with a high frequency of 50 W to generate acetylene plasma in the chamber, and the DLC film was formed. The material was irradiated with acetylene plasma for 30 seconds.

  The first plasma irradiation is not limited as long as the carbon-carbon bond of the DLC film can be broken to generate radicals, and plasma generated using a gas other than acetylene may be irradiated.

Next, the atmosphere inside the chamber was replaced with oxygen (O ₂ ) gas from C ₂ H ₂ to set the internal pressure to 133 Pa. Subsequently, a second plasma irradiation was performed for 30 seconds by applying a high frequency of 50 W to the electrode to generate oxygen plasma inside the chamber.

  The purpose of the second plasma irradiation is to generate a hydrophilic functional group including a carboxyl group by efficiently reacting the radical generated by the first plasma irradiation with oxygen. Therefore, instead of oxygen gas, plasma generated using another gas containing oxygen atoms may be irradiated.

  Next, polyvinylpyrrolidone (abbreviated as PVP), which is a compound obtained by polymerizing N-vinyl-2-pyrrolidone (NVP), was grafted onto the surface of the DLC film into which the carboxyl group was introduced.

  First, the carboxyl group introduced into the DLC film was activated. The activation of the carboxyl group was performed by irradiating with argon plasma. After setting the DLC film into which the carboxyl group was introduced into the chamber, argon gas was flowed to set the internal pressure of the chamber to 133 Pa. Subsequently, a high frequency of 20 W was applied to the electrode and irradiated with argon plasma for 2 minutes.

  After removing the substrate from the chamber, it was exposed to the atmosphere for 1 minute, and enclosed in a glass screw tube together with a toluene solution containing 2 mol / L NVP. After replacing the inside of the glass screw tube with nitrogen, polymerization was carried out at a temperature of 80 ° C. for 20 hours. After polymerization, the substrate was taken out and immersed in a large amount of ethanol and washed to remove unreacted monomers and ungrafted polymer.

  In addition, although plasma irradiation was used for activation of a carboxyl group, you may use an ultraviolet-ray, an electron beam, or a gamma ray.

-Evaluation of DLC film-
The results of evaluating the DLC film produced in this example will be described below. First, functional groups generated on the surface of the DLC film were measured using X-ray photoelectron spectroscopy (XPS). For XPS measurement, an XPS apparatus JPS9010 manufactured by JEOL Ltd. was used, and for the X-ray source, Alkα (1486.5 eV) was used at an output of 100 W (10 kV, 10 mA).

  FIG. 3 (a) shows the result of XPS measurement of the surface of a DLC film that was subjected to first plasma irradiation with acetylene plasma and second plasma irradiation with oxygen plasma, and further exposed to the atmosphere for 2 minutes. ing. A peak of C1s orbital was observed near 289 eV. This peak is a peak based on the O═C—OH bond of the carboxyl group. On the other hand, as shown in FIG. 3B, no peak is observed in the vicinity of 289 eV in the DLC film not subjected to plasma irradiation.

  From this, it is clear that the radical generated in the first plasma irradiation reacts with oxygen to generate a carboxyl group by performing the second plasma irradiation containing oxygen after the first plasma irradiation. .

  FIG. 3C shows the result of XPS measurement of the surface of the DLC film that was exposed to the atmosphere for 2 minutes after only the first plasma irradiation with acetylene plasma. Also in FIG. 3C, the peak derived from the carboxyl group is hardly recognized.

  Further, in FIG. 3A, a peak that is hardly observed in FIGS. 3B and 3C is also observed near 287 eV. This is a peak based on the C—O—H bond of the hydroxyl group, and it can be seen that a hydrophilic hydroxyl group is also generated in addition to the carboxyl group.

  From the above results, it is clear that radicals generated by the first plasma irradiation hardly react with oxygen only by exposure to the atmosphere. That is, in order to efficiently introduce a hydrophilic functional group into the DLC film, the first plasma irradiation for forming the reactive site and the second plasma irradiation using oxygen-containing plasma are indispensable. Is clear.

  Next, the wettability of the surface of the DLC film subjected to the second plasma irradiation was measured with a contact angle measuring device. For the measurement of the contact angle, an automatic contact angle measuring machine DM300 manufactured by Kyowa Interface Science Co., Ltd. was used, and a 1 μL water droplet was placed on the surface of the medical material, and the contact angle was measured. The measured value was an average value of 10 points.

  FIG. 4 shows the change with time of the contact angle after the plasma irradiation. The contact angle of the DLC film not subjected to plasma irradiation indicated by Δ in FIG. 4 was almost constant within the range of 70 to 80 degrees. On the other hand, the contact angle of the DLC film that has been subjected to the first plasma irradiation with acetylene and the second plasma irradiation with oxygen indicated by ◯ is approximately constant at about 3 degrees, and the second plasma irradiation is performed. It can be seen that the hydrophilicity is greatly improved and a so-called superhydrophilic surface is obtained.

  On the other hand, when only the first plasma irradiation with acetylene indicated by ● in FIG. 4 was performed, the initial contact angle was 120 degrees, and the contact angle was larger than that of the DLC film not subjected to plasma irradiation. . In addition, the contact angle decreased with time, and finally reached a slightly larger value than the DLC film not subjected to plasma irradiation. This indicates that the reaction between radicals formed by the first plasma irradiation with acetylene and oxygen in the atmosphere is very slow, and only some of the generated radicals react.

  Further, the results when the first plasma irradiation is performed with oxygen instead of acetylene are indicated by ▽. By using oxygen plasma for the first plasma irradiation, it is expected that the generation of radicals and the reaction with oxygen proceed simultaneously, and the surface of the DLC film becomes hydrophilic. However, in this case, the contact angle once decreased, but a tendency of increasing the contact angle over time was recognized. Although the cause of such behavior is not clear, it is considered that the reaction between the radicals formed in the DLC film and oxygen is not sufficiently generated during the first oxygen plasma irradiation.

  As described above, after the first plasma irradiation for forming a reactive site on the DLC film is performed, the second plasma irradiation with the plasma containing oxygen is performed, so that the contact angle of the DLC film is 10 degrees or less. The so-called super hydrophilic property can be obtained. Further, since it is a DLC film, it is not only superhydrophilic but also durable, so it can be used in various fields including medical materials. Furthermore, by using a functional group introduced into the DLC film, it is possible to fix a polymer or the like to the DLC film and to give a function other than super hydrophilicity.

  5A and 5B show the case where NPV is grafted on the DLC film into which the carboxyl group is introduced by performing the first plasma irradiation with acetylene and the second plasma irradiation with oxygen, respectively, and introducing the carboxyl group. 7 shows the XPS measurement results when NPV is grafted onto a non-DLC film. As shown in FIG. 5A, when a carboxyl group was introduced, a peak of N1s derived from the pyrrolidone ring of polyvinylpyrrolidone was observed. Also, the contact angle, which was about 3 degrees after the second plasma irradiation, increased to 57 ± 3 degrees after the polyvinylpyrrolidone grafting. From this, it is clear that polyvinylpyrrolidone was grafted by the carboxyl group introduced into the DLC film by the second plasma irradiation.

  On the other hand, as shown in FIG. 5B, the peak of N1s is not observed when the carboxyl group is not introduced. This indicates that the carbon-carbon bond of the DLC film is not cleaved and the graft polymerization does not proceed depending on the plasma irradiation conditions used for activating the carboxyl group.

  Further, after the second plasma irradiation, the polyvinyl pyrrolidone was grafted on the DLC film left for 10 days, but the grafting could be performed without any problem.

  As described above, the first plasma irradiation for cleaving the carbon-carbon bond of the DLC film to form radicals and the second plasma irradiation for reacting the radicals formed by the first plasma irradiation with oxygen are performed. Thus, the surface of the DLC film can be made super hydrophilic.

  The reason why the surface of the DLC film becomes superhydrophilic by performing the plasma irradiation twice is not clear, but the reactive site formed by the first plasma irradiation is caused by the second plasma irradiation containing oxygen. This is considered to be because it reacts efficiently and becomes a hydrophilic functional group such as a carboxyl group. Moreover, the hydrophilic functional group introduced into the DLC film is stable and can maintain super hydrophilicity for a long period of time. In addition, the introduced functional groups can be easily activated and the polymer can be grafted. Moreover, it is also possible to use a functional group as a binding site for binding the polymer, and various functions of the polymer can be easily imparted to the DLC film.

  The DLC film imparted with super hydrophilicity or functionality can be used for various applications. For example, stents, catheters, balloon catheters, guide wires, pacemaker leads, indwelling devices, injection needles, scalpels, vacuum blood collection tubes, infusion bags, prefilled syringes, wound holding parts, etc. that require durability and biocompatibility It can be used as a medical device or a material of a medical device.

  The superhydrophilic material, medical material, and medical instrument according to the present invention can improve the hydrophilicity of the DLC film and can efficiently impart functions such as biocompatibility. In addition to being useful as a modification method, it is useful as a super-hydrophilic material, a medical material, a medical instrument and a method for producing the same.

DESCRIPTION OF SYMBOLS 1 Target 2 DC arc discharge plasma generator 11 Target 21 Chamber 22 Vacuum pump 23 Electrode 24 Electrode 25 High frequency power supply 26 Matching network

Claims (8)

A substrate;
A DLC film formed on the surface of the substrate and having a hydrophilic functional group,
Between the base material and the DLC film, an intermediate layer for improving the adhesion between the base material and the DLC film is provided,
The contact angle of water on the surface of the DLC film is 10 degrees or less,
The DLC film has a thickness of 0.01 μm or more and 3 μm or less,
The intermediate layer has a thickness of 0.01 μm or more and 0.3 μm or less.   The superhydrophilic material according to claim 1, wherein the hydrophilic functional group includes at least a carboxyl group.   The super-hydrophilic material according to claim 1 or 2, wherein the base material is a metal material, a ceramic material, a polymer material, or a composite thereof.   4. The superhydrophilic material according to claim 1, wherein the intermediate layer is an amorphous film mainly composed of silicon and carbon. 5.   The medical material using the super hydrophilic material of any one of Claims 1-4.   A medical instrument using the medical material according to claim 5.   The medical device according to claim 6, wherein the medical device is in direct contact with human tissue.   The medical device is any one of a stent, a catheter, a balloon catheter, a guide wire, a pacemaker lead, an indwelling device, a syringe needle, a scalpel, a vacuum blood collection tube, an infusion bag, a prefilled syringe, and a wound holding part. The medical instrument according to claim 6 or 7, characterized by the above.

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